Process of treating commercial calcium cyanamid.



To all 'wk'om 2'25 may concern: i

ferti lize rs some .said phosphates is or may be changed from a as upon sowing or spreading lime-nitro en or caustic lime 'cya 11 amid FRANK S. WASHIBURN, OF NASHVILLE, TENNESSEE.

PROCESS OF TREATING COMMERCIAL CALCIUM CYANAMID.

N 0 Drawing.

Be it known that I, FRANK S. Wasnnunx, F a citizen of the Unitet States, residing at Nashville, in the county of Davidson and 1 State of 'lennessee, have invented certain 5 new and useful I m n-ovements in Processes of Treating Commercial (alcium Cyanamid; l and'I (lo-hereby declare the following to be a full, clear, and exact description of the'l invention, such as will enable others skilled in the art to which it appertains to make and use the same.

This invention i treating conn'nercia l monly known as lilne nitrogen and has for l its object to produce an improved product i relates to a process of 1 calcium eyanamid comwhich will be free from the disadvantages now found to accompany the shipping storing, mixing with other fertilizer material, as well as sowing of the present product upon the soil.

To these ends the invention consists in the novel steps constituting my process as well in the improved resulting product, all as will be more fully hereinafter disclosed and particularly pointed out in the claims.

In order that my invention may be more clearly understoodthe above obstacles that are encountered may be briefly summarized as follows :-Durin shipping and storing the lime nitrogen often swells and bursts its containers; upon mixing" the lime nitrogen with phosphates and other materials to form of the phosphoricacid of l l l soluble to an insoluble form; and during this step of compounding fertilizers as well the lime nitrodust is objecas well as to l l l gen upon the soil its very line i tionable both to the workmen I the farmer. The reason for the bursting of the bags resides in the fact that unhydrated contains among other things i when made about 20% of calcium oxid, (210, l and the commercial calcium l or hydrated lime-nitrogen contains among other things about 25% of ca'll ciumhydrate Ca(OH). ,and not infrequently l a few percent. of calcium oxid. Therefore the commercial lime nitrogen takes up moisl ture of the airflthc mass thereupon swells, l and sometime;- bursts the containers. In adl dition to the time above nrmtioned commerj cizll calcium cyanainid contains sayrabout 25 l Specification of Letters Patent. Application filed June 3, 1912.

atented Feb. 18,1913. Serial No. 701,379.

per cent. of calcium chemically combined by rather weak bonds in the fOl'l'l'l of CaCNi as well as other ingrediei'it's not necessary to discuss and the reason why upon mixing with phosphatic materials lime nitrogen tends to cansi a reversion of the soluble bhosphoric acid into the insoluble form resides in the fact. that the calcium hydrate Ca(()ll). and the free lime CaO, as well as the calcium cyanamid CaCN. are found to have a tendency to change soluble forms of phosphoric acid into insoluble forms when mixed with the ordinary acid phosphate used in making up or compounding fertilizers. Such reversion of course constitutes an objection to the commercial employment of lime nitrogen in such fertilizer mixtures and the tendency to the same will be more readily understood from the following possible equations when free lime is added in" ditl'erent proportions (1) l, .3I-l' la():

- P 0 11210.2H O.+I-I O. A further addition of lime produces (2) l. -,.Ca().2ll O-l-CaO:

130 2021011 0+H O. A large excess of lime may produce (:5) l. .2(a().I-IJH CaO:

P O .3Ga()+I-l Similarly calcium hydrate, (la(()ll), will react as followsz (4;) zl'l lt)V,+Ca(() li) (la I'l ,1 -l-2lli Uall ,l +(a(()l-l). (va. ,ll. ,l. .+2.ll.

(ti) (ait r o teno in addition to these reactions of reversion there is also another one of importance which can occur as follows:

()n heating to about t1t) C, or higher reaction (7) proceeds and causes a loss of a portion of the citrate soluble acid by reversion to the insoluble tri-calcium phosphate. As each reaction (1) to (6) inclusive evolves heat it is easy to see that the mass can be UNITED STATES; retrain OFFICE.

the requisite temperature l itself also reverts phosphates according to to take place even by the I the reactions i aratively small amount 2 5 2 i) I readily heated to for equation (7) piesience of a com 1 d h ime or even 0 ca cium hy rate. T e

heat evolution of reactions (4), (5), and E (6) are less than those of (1), (2), and (3), (14) P O .CaO.2H Ol-CaCN,= the dlffl'efienfie dbeing due to the decomposil- P .2CaO.H O-l-HI CN tion 0 t e y rate on the left-hand side 0 e uations i), (5), and (6). In the rocess i i 3 :b ON

o hydration advantage may be ta en of this lower heat of reaction when the product These reactions also evolve heat in considerable amount. Exact data as tothe is mixedivvith acid phosphate, as thereby the reaction (7 1s greatly hindered. Specific heat evolution is not available, but from my datagiving the heats of formation as well experiments it seems-to be about equal to 15 as other chemical data connected with these that evolved by calcium hydrate in correequatious' are om1tted, for the sake of clearspe di reactlqns. p I 'I l 1S Sa 1d lithe lime had e It thus ap ars there is a'whole series of converted mto calcium carb nate bef r m reactions evo' vin more or less heat and all mg with the acid phosphate, reactlons of tending raise the temperature of the mix conversion w1ll st1ll take place, but with a much lessened intensity as far as the heat evolution is concerned. The difierence inthis case is due to the heat absorbed in the decomposition of the carbonate. The reactions l ivnlyed when calcium carbonate is added indifferent proportions are ture ofe; id phosphate and lime nitrogenand to cause a reversion according toone or more of the reactions given. It is therefore apparent if the lime can be a chemical compound the heat evolution and chemical activity will be considerably reduced. The thermal data accompanying the reactions involving the fixation of lime in the carbonate form show this fact clearly. The solution of the reversing cordingly resides in an acid that will fix 3 rs' a 'i' z the lime in such a stable form that it will P Q 2(j H ()+C5CO not be decomposed by the acid phosphate. P Q 3(), O +H +CO Carbon dioxid 1s found not quite strong enough in itself,-and besides it adds a very It IS not hkely that reactlon could large amount of inert material of-no ferti- It is also found when lime nitrogen is mixed with ammonium sulfate, owin to an absence of an excess of acid. certain proportions of ammonia are evolve from the sulfate and-therefore a valuable fertilizer constituent is lost.

have been made in the i the take place in the case of commericial cyan-- amid, or lime nitrogen.- The above indicates the marked advantages of combining the lime present with an acid to a stable salt, for the carbonate shows very little or in exceptional cases a negative value for the heat evolved on mixing witacid phosphate. This of course hinders the lizing value.

past to overcome development of reaction to a Very great free lime in the lime nitrogen. But all or extent- We must not lose i t of the fact these attempts seem to havebeen along the however, that the carbon dioxid developed line of neutralizing the free lime and form in reactions (8) to (10) inclusive can react jug neutral and stable salts.

combined in.

problem ac- For example,

on i -y af according to the following sulfuric acid has beenadded to lime nitroequa gen in suflicient quantity to form calcium to (11) CaCN +H,O+CO.: sulfate with the free lime'present. But

I li CN -(laCt) while the calcium-sulfate possessed the de- (12) CaGN2+2H2O+CO2: the whole 0 t' pera ion m practice was found CaCO3+CO (NH2)2' to be complicated and expensive, since it in- 55 Both these reactions evolve heat and help volved the use of an excess of acid and at to raise the temperature of the mixture when the same time part of the calcium cyanam d allowed to take place. The heat evolutions had to be decomposedby the sulfuric acld however cannot be given at present because in order to insure stab lity. A modification such thermochemical data for cyanamid of this acid neutralization is disclosed in the lacking. ltulian Patent No. 98,374, May 13, 1908 to In addition to the above obstacles that Barzand and Zanardo, in which the invenlime nitrogen and tors proposed to neutralize ,the free lime by are met with in using which are due to the presence of lime CaO, the use of acid anhydrids in the gaseous form. Similarly, German Patent No.

to calcium hydrate Ca(OH) or to calcium 235,754, June 16, 1909 to O. F. Carlson,

65 carbonate CaCO. calcium cyanamid CaCN sired qualities to a greater or less degree,-

addition tends to make the particles oftlte cyanami'd or lime nitrogen agglomerate or granulate, and at. the. same time assists in preventing dusting or the fine particles. If now a mixture of-lime nitrogen and stick water is further treated with carbon dioxid condition, an additional marked decrease in the chemical activity of the product will be noted toward acid phosphates. This decreaseot' chemical activity is found to, be even very marked in such cases where the amount of carbon dioxid absorbed is very materially less than would be required to form calcium carbonate with all the calcium present in the original lime nitrogenorcyanamid.

proposes to render lime-nitrogen non-caustic by. treating it with carbonic acid or carbon dioxid with or without the addition of water. U. S. Patent No. 982,311, January 24, 1911 to Stilleson discloses substantially the same thing. The absorption of carbon dioxid by dry lime nitrogen, however, is a slow operation and promises little success; and although the rate of absorption can be increased by the addition of water before or with the carbon dioxid gas, yet the dis advantage of the carbonated product is that some 10 to 20 per cent. of material of no fertilizing value has to be added to the lime nitrogen, While such carbonated lime nitrogen is not greatly lessened in chemical activity toward acid phosphates and ammonium sulfate. According to my invention, on the other hand, now to be disclosed, the above objections are removed. That is to say I have discovered that if instead of using ordinary water for hydration, one makes use of con'nnercial stick water which contains amino acids and is a byproduct of the meat packing industry containing various ingredients of an organic nature boiled down to a sort of broth or solution of varying proportions of solids to water, the free lime and probably some of the calcium in the cyanamid (caON combines with the organic con'ipounds of the Stick water which upon evaporation of the water represent the solids therein, in preference to the water present. Combined in this way the active caustic properties of the lime nitrogen are greatly decreased, or entirely neutralized according to the quantity of stick water used. And such treated material shows a less chemical action or tendency to reversion of the phosphoric acid of an acid phosphate. Further, a good influence has been gained through the addition of a material of recognized fertilizing value instead of one inert character, as heretofore. illiquid stick or stick water, having 50% moisture, contains ap noximately 7% of nitrogen, and is in the form of a comparatively thin. liquid. But in this form, notwithstanding its very high fertilizing value, it is impractimble of use as a fertilizer material until after it has passed through an expensive and complicated eva 'iorating prooess in which it is il'tll'lRfOl'll'lQtl into a commercial fertilizer material known as concentrated tankage. Even when so reduced, it is gummy and soggy and difficult of incorporating with other materials into the product commonly sold to farmers as a tertil zer. This stick water could be replaced by any organic material having similar combining properties with lime, for example such as sugar beet refuse, beet sugar molasses, steep water from starch manufacture, tannery waste, etc. In addition to this neutralization of the free lime, the stick water been treated with stick water and-carbon dioxid show but a slight gain in weight on long standing in the air and the resulting products represent over products treated by any of the previously known processes. Lime nitrogen alone when treated with stick water agglomerates or granulates; and similarly the product treated with stick water and carbon dioxid shows agglomeration. Lime nitrogen treated .with stick water and carbon dioxid shows decreased dusting properties, as above stated, and it is further found this decrease can be still further emphasized by the addition of a suitable oil to the mass after the treatment with the stick water and the car bon dioxid. Further, by subjecting the calcium cyanamid itself CaQN to the action of carbon dioxid C0,. after the treatment with stick water, there being less caustic lime Cat) present, it does not require so much gas or other acid anhydrid to convert the calcium cyanamid into the form of the byd rogen cyanamid H. .CN,, in accordance with the .following equation In other words, only substantially enough gas is required to carry out this reaction while it free calcium oxid is also present, an additional quantity of gas of course would be required. Of course, urea, CO(Nl,-l as as well as other nitrogenous compounds can be economically formed in from the calcium cyanamid.

It. will thus be seen that my process enables me to obviate the above objections causing the containers to burst during shiping and storing; causing the atmosphere to be filled with a disagreeable dust during the compoumling of fertilizer materials and during the sowing of the lime nitrogen on the soil; and also causing some of the phosphoric acid of the mixed materials to. change from the soluble to the insoluble form. Furthcr'it will be observed that the lime nitrogen pr duct resulting from my process difthe same way floating around of' 'hile still in the. moist Such mixtures of lime nitrogen and phosphates after the lime nitrogen has marked improvements fers from the present lime nitrogen product in that it contains substantially no free caustic lime, is in an agglutinated or granulated condition instead of in the conditon of a free dusting, very fine impalpable powder; it contains substantially no phosphoric acid in an insoluble form; and it is combined with a nitrogenous material having a fertilizing value.

It is obvious that those skilled in the art may vary' my process as Well as my improved product without departing from the spirit of my invention, and therefore I do not Wish to be limited to the above disclosure exce t as may be required by the claims;

W at I claim is 1. The process of neutralizing the free calcium oxid, CaO, carried by commercial calcium cyanamid Which comprises causing the same to react With'an organic material itself having a fertilizing value; and in treating 'the mixture with carbon dioxid, CO substantially as described.

2. The herein described improved product comprising commercial calcium cyanamid substantially free from ,free calcium oxid, CaO in an agglutinated condition; and having admixed therewith carbonic acid and stick Water, substantially as described.

3. The herein described improved product consisting of commercial calcium cyanamid substantially free from free'calcium oxid, CaO in an agglutinated condition; and having admixed therewith stick Water and oil,-

substantially as described.

In testimony whereof, I aflix my signature, in presence of two Witnesses.

FRANK S. WASHBURN.

Witnesses: v

E. J. PRANKE, H. A. BLACK. 

